Lateral retractor system and methods of use

ABSTRACT

Technology disclosed herein relates to retractors and methods of use for surgical procedures, and in particular, spinal surgical procedures. In one embodiment, a surgical retractor includes a pair of pivotable armatures and a translatable armature. A body for supporting the armatures is provided, with a handle connected thereto. The handle includes a first rotary actuator, wherein a rotation of the first rotary actuator moves the pair of pivotable armatures in opposite arcuate directions, and a second rotary actuator, wherein a rotation of the second rotary actuator translates the translatable armature in a linear direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalApplication Ser. No. 61/529,756, filed Aug. 31, 2011, entitled, “LateralRetractor System and Methods of Use,” the disclosure of which is herebyincorporated by reference herein in its entirety.

INTRODUCTION

Current retractor systems for lateral spine surgical procedures createan opening through the side of a patient, and may pass through the psoasmuscle. Improved systems are desirable with respect to at least ease ofuse, stability, visibility and robustness.

SUMMARY

In one aspect, the technology relates to retractors and methods of usefor surgical procedures, and in particular, spinal surgical procedures.In one embodiment, a surgical retractor includes a pair of pivotablearmatures and a translatable armature. A body for supporting thearmatures is provided, with a handle connected thereto. The handleincludes a first rotary actuator, wherein a rotation of the first rotaryactuator moves the pair of pivotable armatures in opposite arcuatedirections, and a second rotary actuator, wherein a rotation of thesecond rotary actuator translates the translatable armature in a lineardirection.

In one embodiment, a method of creating a distraction corridor to asurgical site is disclosed. The method includes providing a surgicalretractor having a handle comprising two rotatable elements, and aplurality of blades moveable relative to the handle. The method includesinserting the plurality of blades simultaneously into a body tissue;actuating a first of the two rotatable elements so as to separate atleast two of the plurality of blades; and actuating a second of the tworotatable elements so as to translate at least one of the plurality ofblades.

BRIEF DESCRIPTION OF THE DRAWINGS

There are shown in the drawings, embodiments which are presentlypreferred, it being understood, however, that the technology is notlimited to the precise arrangements and instrumentalities shown.

FIG. 1 depicts a perspective view of a retractor device in an openposition.

FIG. 2 depicts a partial enlarged top view of a retractor device with atop cover removed.

FIG. 3A depicts a top view of a retractor device in a closed position.

FIG. 3B depicts a top view of a retractor device in an open position.

FIG. 4 depicts a partial exploded perspective view of a handle of aretractor device.

FIGS. 5A-5C depict enlarged partial perspective views of a lockingelement in various positions.

FIGS. 6A-6C depict enlarged partial views of a blade/arm interface of aretractor device.

FIG. 7 depicts a side view and enlarged partial side views of a dilator.

FIGS. 8A and 8B depict a perspective view of an intradiscal shim, andthe intradiscal shim extending from a blade, respectively.

FIGS. 8C and 8D depict a perspective view of a widening shim, and thewidening shim connected to a blade, respectively.

FIGS. 8E and 8F depict a perspective view of a lengthening shim, and thelengthening shim connected to a blade, respectively.

FIG. 8G depicts a sectional view of the intradiscal shim and blade ofFIG. 8B.

FIGS. 8H and 8I depict a perspective view of a first anchoring shim, andthe first anchoring shim connected to a blade, respectively.

FIGS. 8J and 8K depict a perspective view of a second anchoring shim,and the second anchoring shim connected to a blade, respectively.

FIGS. 8L and 8M depict a perspective view of a third anchoring shim, andthe third anchoring shim connected to a blade, respectively.

FIG. 8N depicts a perspective view of a fourth anchoring shim connectedto a blade.

FIGS. 9A-9F depict a method of using a retractor system for a lateralspinal surgical procedure.

FIG. 9G depicts a paddle for use with a retractor system.

FIGS. 10A and 10B depict a method of using a retractor system.

DETAILED DESCRIPTION

FIG. 1 depicts a retractor device 100 that includes a main retractorbody 126, a handle 114, and a plurality of armatures (arms) 102-106 withblades 118-122 attached thereto. The retractor body 126 includes anumber of components that drive the operable elements of the retractordevice 100. The arms 102-106 may be opened and closed by rotatingactuators 128, 130 on the handle 114. The blades 118-122 attached toeach arm 102-106 are used to form a surgical distraction corridor in abody tissue. This corridor is enlarged as the arms 102-106 are opened.These and other elements of the retractor device 100 are described inmore detail below.

In the depicted embodiment, the retractor body 126 includes a top coverplate 108 and a bottom cover plate (not seen in FIG. 1) that limitaccess to the drive elements located therein. The top cover 108 plateincludes one or more slots 116. In some embodiments, each of the twopivoting arms 102, 106 is connected to a guide pin (not seen in FIG. 1).The pin is located within the slot 116, and restricts movement of thearm 102, 106 to which it is connected as the arm 102, 106 is opened andclosed. In the depicted embodiment, a slot 116 is associated with eachof the pivoting arms, with two pins and slots 116 operating together torestrict the movement of arms 102, 106. In other embodiments, only asingle slot 116 may be used. In certain embodiments, the slot(s) 116 maybe entirely eliminated. Inclusion of the slot 116, however, helpscontrol the connection between the pivoting arm 102, 106 and theretractor body 126. One or more articulating arm connection points 110,124 may also be located on the top cover 108. These connection points110, 124 may be used to connect the retractor device 100 to a discretearticulating arm that is connected to a surgical table or othersubstantial element. Rigid connection of the retractor device 100 to thesurgical table or other fixed structure allows the device 100 to be heldin place, so the surgeon may be free to perform other aspects of aprocedure without having to hold the retractor device 100.

The retractor body 126 is connected to a handle 114 that may bedisengageable, as described below. In the depicted embodiment, thehandle 114 includes two rotatable actuators 128, 130 that are used toactuate the arms of the retractor device 100. In some embodiments,rotation of the main retractor actuator 128 (centrally located on thehandle 114 in the depicted embodiment) actuates the two pivoting arms(i.e., the cranial and caudal arms 102, 106). In some embodiments,rotation of the posterior actuator 130 (located at the end of the handle114 in the depicted embodiment) actuates the posterior arm 104. Inalternative embodiments, the position of the actuators 128, 130 may beswitched or otherwise vary. In other embodiments, each armature has aseparate handle rotatable actuator to allow the armatures to be openedindividually. In still other embodiments, the handle contains a singlerotatable actuator that actuates all of the armatures simultaneously.The rotational axis A is shared by both the main retractor actuator 128and the posterior actuator 130. In alternative embodiments, otheractuator elements may be used. In one example, the actuator element forthe pivoting arms may be a circular disc having an axis of rotationsubstantially orthogonal to the axis A of the handle 114. The disc maybe connected to a worm gear, lead screw (FIG. 2), or other elementwithin the handle 114 that operates the pivoting arms 102, 106. Asimilar disc may be used for the posterior arm 104. Alternatively, atranslating element, for example a slide movable parallel to the axis ofthe handle 114, may be used to actuate the posterior arm 104. Asdescribed in more detail below, some or all of the handle 114 may beremovably connected to the retractor body 126. A connection element 112may connect the handle 114 to the retractor body 126. In certainembodiments, the connection element 112 incorporates a lock havingmultiple positions and functions as described below with regard to FIGS.5A-5C.

In some embodiments, retractor 100 includes three arms 102-106 used tohelp form a surgical distraction corridor in a body tissue. In somecases, arms 102-106 include two pivoting arms 102, 106 and onetranslating arm 104, with each or some having a blade 118-122 extendingtherefrom. A first end of each of the pivoting arms 102, 106 is attachedto the retractor body 126. The opposite end of each arm 102, 106 issecured to a blade 118, 120 that is inserted into the body tissue. Forcertain embodiments, such as when retractor 100 is used in a lateralspinal surgical procedure, the terms “cranial” and “caudal” may beassociated with certain arms 102, 106 and blades 118, 120 to helpidentify their position relative to the patient. For example, arm 102and blade 120 may be referred to as caudal arm 102 and caudal blade 120.Similarly, arm 106 and blade 118 may be referred to as a cranial arm 106and cranial blade 118. In that regard, the cranial blade 118 is locatedon the side of the retractor 100 closest to the head of the patient,while the caudal blade 120 is located on the side of the retractor 100closest to the legs. The cranial and caudal blades 118, 120 aresimilarly configured, such that either blade 118, 120 may be consideredeither the cranial or caudal blade, depending on which side the patientis laying during a surgical procedure. In one embodiment, both pivotingarms 102, 106 (and therefore both blades 118, 120), pivot in an arcuatedirection away from a centerline of the retractor device 100, defined bythe axis A of the handle 114, as the main actuator 128 is rotated. Ofcourse, other embodiments of the retractor device may be configured suchthat separate actuators are used for each of the two pivoting arms 102,106. Using a single actuator for both pivoting blades 118, 120, however,helps ensure even opening of the surgical corridor during use and abalancing of forces against the blades 118, 120.

The translating arm 104 has first and second ends, with the first endconnected to the main retractor body 126 and the second end connected toa blade 122. The translating arm 104 may be referred to as the posteriorarm 104 and is configured to move axially along the axis A. That is, thearm 104 may be drawn into and extended out of the retractor body 126, asthe posterior actuator 130 is actuated. The posterior arm 104 may alsoinclude an articulating arm connection element 132, thereby providing anadditional point of connection of the retractor device 100 to thesurgical table or other secure structure. The posterior blade 122 issecured to the translating arm 104, either directly or with a pivotableconnection as described above with regard to the blades 118, 120.Additionally, although the device 100 is typically utilized such thatthe handle 114 is pointed toward the surgeon, the device 100 may also beoriented so that the handle 114 is pointed away from the surgeon duringuse. In that case, the translating arm 104 may be referred to as ananterior arm 104.

FIG. 2 depicts an embodiment of the drive mechanisms for opening andclosing the arms 102-106 of the retractor device 100. As shown, a mainworm drive mechanism 214 or lead screw is used to actuate the cranialand caudal arms 102, 106. Rotation of the main worm drive 214 by themain actuator 128 (not shown) rotates the main worm gears 210, 212,thereby separating or pivoting the cranial and caudal arms 102, 106. Insome embodiments, worm drive 214 engages teeth on worm gears 210, 212.In one embodiment, the use of a worm drive mechanism 214 to separate thecranial 118 and caudal blades 120 allows for a large number of openpositions between the blades 118, 120. In some cases, the worm drivemechanism 214 provides an unlimited number of open positions dependingon the amount of rotation of main worm drive 214. Additionally, theblades 118, 120 are brought together using the worm drive mechanism 214.In other words, the worm driver 214 and worm gear mechanisms 210, 212prevent the cranial arm 102 and caudal arm 106 from moving unlessspecifically actuated. In this manner, the blades 118, 120 aremaintained in a desired position until the worm drive mechanism 214 isactuated to further open or close the blades 118, 120. A posterior driveelement may be a lead screw 204 mechanism that is engaged with a leadnut 202 to the translating arm 104, allowing for movement of thetranslating arm 104. In the depicted retractor device 100, the shaftthat connects the lead screw 204 to the posterior actuator 130 passesthrough the main worm drive 214 that activates the cranial and caudalarms 102, 106. As with the worm drive 214, forces applied directly tothe posterior blade 122 or arm 104 will not move those elements,compared to a ratchet-type or other system.

FIGS. 3A and 3B depict the retractor device 100 in closed and openpositions, respectively. When in the closed position, in one embodiment,the blades 118-122 form a perimeter that is configured to surround oneor more generally round dilators (FIG. 7) that are first introduced intoa body tissue. These dilators and the use thereof, are further describedbelow. The blades 118-122 need not abut one another but may be soconfigured if desired. Gaps or spaces between the blades 118-122 when inthe closed position are generally not a concern unless these gaps arelarge enough to allow creep of tissue between the blades 118-122. In aparticular embodiment, a gap exists between the cranial blade 118 andthe caudal blade 120, even when the cranial arm 106 and caudal arm 102are in a closed and abutting position. In some embodiments the gapextends the entire length of blades 118 and 120. Rotating the mainactuator 128 located on the handle 114 moves the arms and the blades118, 120 away from each other, in arcuate directions. Rotation of theposterior actuator 130 moves the posterior arm 104 and blade 122. Whenthe blades 118-122 are inserted into a body tissue, this movement forcesthe tissue apart, creating a surgical corridor, the interior of whichmay be accessed by a surgeon.

FIG. 4 depicts a partial exploded view of an embodiment of the handle114, specifically, the portion of the handle 114 that actuates thecranial and caudal arms 102, 106. The main actuator 128 portion of thehandle 114 is connected to an elongate shaft 408. The connectionelement/lock 112 includes an internal thread connection 404 that mateswith a corresponding thread connection 404′ on a friction sleeve 402.Rotation of the connection element/lock 112 rotates the friction sleeve402. A number of locking elements 406 project from the friction sleeve402 and engage with a collar 416. As the locking elements 406 engagewith the collar 416, functionality of the retractor device 100 changes,as described with regard to FIGS. 5A-5C. Collar 416 is coupled to core410. In one embodiment, pins 412 couple collar 416 to core 410 and arewelded or otherwise affixed in place.

FIG. 5A depicts a first position of the connection element 112, as thatelement engages with the collar 412. In this position, referred to as a“soft engagement” position, ball bearings 414 are free to move withinthe constraints of a C-spring 502, because of openings 418 presentbetween the locking elements 406 of the friction sleeve 402. FIG. 5Bdepicts a second position, wherein the connection element 112 is rotateda desired or set amount, such as about thirty (30) degrees, aboutforty-five (45) degrees, about sixty (60) degrees, or the like. In thisposition, the locking elements 406 are moved forward, such that theC-spring 502 is locked out, thereby restricting movement of the ballbearing 414. This position captures the shaft 406 and allows theretractor arms to be opened and closed. FIG. 5C depicts a thirdposition, wherein the connection element 112 is rotated an additionaldesired or set amount, such as about another thirty (30) degrees, aboutanother forty-five (45) degrees, about another sixty (60) degrees, orthe like. This moves the friction sleeve 402, and therefore the lockingelements 406, further forward so as to engage a corresponding toothedplate in the retractor body 126. In this position, the friction sleeve402 is in the fully locked position, such that the gaps 418 arerestricting the C-spring 502 from expanding. This locks the ballbearings 414 in place, and the locking elements 406 are in a positionwhere they will interface with the corresponding teeth in the retractorbody 126 (not shown). The center core 410, the handle body, and thecollar 416 are fixed relative to each other, using a variety oftechniques. For example, in one embodiment pins 412 couple collar 416 tocore 410.

FIGS. 6A-6C depict enlarged partial views of a blade/arm interface 600,and show various technologies incorporated therein. FIG. 6A depicts anend of the cranial arm 106, and blade 118. The blade 118 is pivotablyconnected to the arm 106, specifically with a blade base 604 that ispositionable within a toeing cut-out 606 in the arm 106. In oneembodiment, blade 118 has a curved proximal end which engages the bladebase portion of arm 106. The blade base 604, in one embodiment, isrotatably coupled to arm 106. In this embodiment, a blade attachmentmechanism, depicted in FIG. 6B as a screw 612, threads through a hole inblade 118 proximal end and into a threaded opening in the top of bladebase 604. Once blade 118 is coupled to the blade base 604 of arm 106,rotation of the blade base 604 allows the distal end of blade 118 to betoed in a desired direction as described below. In a particularembodiment, a toeing screw 608 is coupled to the blade base 604.Rotation of toeing screw 608 causes movement of the blade base 604relative to arm 106. In a particular embodiment, toeing screw 608extends through a threaded hole in blade base 604. Further rotation oftoeing screw 608 causes the tip portion of screw 608 to engage toeingcut-out 606 and thereafter provide for rotation of the blade base 604relative to cut-out 606. In this manner, blade 118 also rotates, whichallows the distal end of the blade 118 to move past its initialorientation that is generally orthogonal to the arm 106. In certainembodiments, each of the cranial and caudal blades may be toed up toabout ten (10) degrees, up to about twenty (20) degrees, or up to aboutthirty (30) degrees from orthogonal. In a preferred embodiment, thetoeing of blades 118, 120 allows the distal ends of blades 118, 120 tobe toed outwards, providing a larger opening near the operative site.Regardless of the maximum toeing angle, the toeing screw 608 allows forinfinite degrees of variability across the entire range of motion. Incertain embodiments, the posterior blade (not shown) may be toed aswell, although the posterior blade 122 typically does not have toeingability. This toeing functionality may also be incorporated into thecaudal arm 102, as depicted in FIG. 6B. While the depicted embodimentshows blade 118 proximal end coupled to a rotatable blade base 604, inanother embodiment the proximal end of blade 118 includes structure forproviding the rotation function. In this manner, the blade 118 is firmlycoupled to the arm 106, but provides the rotation for a controlledtoeing function.

FIG. 6B also depicts one or more channels 602 on the blade 120 that eachmay receive a probe, a K-wire, a stimulation electrode, or the like. Insome embodiments, the stimulation electrode may be used to detect thelocation, and/or proximity of nerves in the target area, which may helpavoid damage to the nerves. FIG. 6C depicts a rear perspective view ofthe caudal blade 120 of FIG. 6B. The channel 602 for receiving the probemay be a substantially open slot along a rear face of the blade 118, asdepicted in FIG. 6C. In general, the channel 602 may extend to a distalend of the blade 118, such that the electrode may detect the locationand/or proximity of any nerves once it is advanced into the tissue. Ofcourse, channels 602 may be located elsewhere on the blade 118 as well.In certain embodiments, the channel 602 extends along only a portion ofthe length of the blade 118, or is not present at all. In someembodiments, the channel 602 has a jog, a bend, or a narrowed regionalong at least a portion of the length of channel 602. In someembodiments, the jog or bend is near the distal end of blade 118. Inthis manner, the elongated flexible element, such as a K-wire or probe,inserted into the channel 602 is at least partly held in place withinchannel 602 due to the increased friction needed to move the flexibleelement relative to the jog, bend or narrowed portion. This feature maybe useful, for example, to help maintain the flexible element withinchannel 602 while blade 118 is being inserted or removed from thepatient tissue.

FIG. 7 depicts side and enlarged partial side views of a dilator 700that may be used in conjunction with the retractor depicted herein. Oneor more dilators 700 may be used to further increase a diameter of aninitial distraction corridor as described in more detail below. Similarto the channel located on the retractor blade(s), a channel 702 may alsobe located on the dilator(s) 700, and may be sized to accommodate astimulation electrode, a probe, or other elongate element. In certainembodiments, a single stimulating electrode may be used with eachcomponent (e.g., a first dilator, a second dilator, retractor blade)introduced into the body tissue. After insertion of the first dilator,the electrode may be withdrawn and inserted into a channel of a nextdilator, then into a channel in a retractor blade, until the blades areopened, thereby creating the desired surgical corridor. In someembodiments, a top surface 708 of the proximal end 704 may beconstructed of hardened material to allow the dilator 700 to be impactedwith an object such as a hammer during insertion. In a particularembodiment, dilator 700 comprises anodized aluminum, with the proximalend 704 comprising a steel impaction cap. In this manner, the proximalend may be struck with a hammer or other impaction tool with little tono deformation of proximal end 704. In some embodiments, proximal end704 may be flared (much like the head of a nail). At least a portion ofthe distal end 706 may be tapered to ease insertion into the initialdistraction corridor.

FIGS. 8A-8F depict various embodiments of shims that may be used inconjunction with a retractor device such as described herein. In thedepicted embodiments, some of the shims include one or more tabs 806 orother mechanisms to engage a ratcheted groove 804 located on theinterior face of the blades 802. The tab/ratchet interface allows thedepth of insertion of the shim to be adjusted based on the needs of thesurgeon performing the particular procedure, and the groove 804 isconfigured such that multiple depths may be achieved. In the depictedembodiment, the groove 804 comprises two opposing ratcheted surfacesthat are engaged by opposing tabs 806 on the shim which is, in thiscase, an intradiscal shim 810. In some embodiments, tabs 806 extend fromflexible arms 808 that may be deflected inward, such as by an elongateinstrument used for shim insertion or retraction. Tab 806 is disengagedfrom the groove 804, allowing the shim 810 to be moved upward ordownward along the blade 802. In some embodiments, arms 808 arecompressed towards each other to allow shim 810 to slidingly engage theblade 802 without a ratcheting of tabs 806 and groove 804. The outeredges of shim 810 may engage a corresponding feature in blade 802 toallow a sliding or telescoping movement between shim 810 and blade 802.In some embodiments, one or more outer edges of shim 810 engage a slot,a groove, a lip, an overhang, or the like in blade 802 to provide for acontrolled sliding movement of shim 810 relative to blade 802. In thismanner, the shim 810 may be adjusted to a desired position relative toblade 802, and then released to securely lock in place using tabs 806and groove 804. This arrangement also helps prevent the shim 810 fromdisengaging from blade 802. The depicted intradiscal shim 810 may beused to fix a position of one of the blades 802 (typically, theposterior blade) relative to a spine. The distal tip 812 of theintradiscal shim 810 is sized and configured so as to be temporarilylodged between two vertebrae during a spinal procedure. The intradiscalshim 810 may, for example, restrict lateral movement of the blade 802 towhich the shim 810 is attached. Intradiscal shim 810 also helps restrictblade 802 movement in the cranial-caudal directions, and theanterior-posterior directions as well. A widening shim 814 is depictedin FIGS. 8C and 8D and is used, inter alia, to prevent tissue creep intothe spaces between the blades 802 when they are opened. A lengtheningshim 816 is depicted in FIGS. 8E and 8F and is used to lengthen theeffective depth of penetration of the blades 802, allowing a deepersurgical corridor to be opened in a body tissue. In general, thewidening and lengthening shim 814, 816 are utilized on the cranial andcaudal blades. In some embodiments, the shims 810, 814, 816 areinterchangeable, with each available for use with any of the retractorblades 802.

While the widening shim 814 and lengthening shim 816 are each depictedas discrete from the blades 802, in alternative embodiments they may benon-removably coupled to the blades 802 prior to insertion into the bodytissue. In a particular embodiment, intradiscal shim 810 is slidably andnon-removably coupled to the posterior blade. This helps prevent theshim 810 from inadvertently disconnecting from the blade 802, whichwould defeat the purpose of using an intradiscal shim 810 to fix theposition of the blade 802 in the body. In this manner, the intradiscalshim 810 operates as an extension of the retractor blade 802 when adistal tip 812 of the shim 810 is positioned to extend beyond the distaltip of the retractor blade 802. When not in use, the shim 810 iswithdrawn into the retractor blade 802 such that the distal tip 812 ofthe shim 810 does not extend beyond the distal tip of the retractorblade 802.

A configuration of such a blade/shim interface where the shim is notremovable from the blade 802 is depicted in FIG. 8G. The shim 810 andblade 802 are coupled together in a manner to allow a slidablerelationship between the shim 810 and the blade 802. In the depictedembodiment, inner edges 818 of the blade 802 substantially surroundwings 820 of the shim 810, which prevents the shim 810 from being pulledaway from the blade 802. A travel stop 822 is located at a bottom of theblade groove 804 or adjacent the blade groove 804. The travel stop 822prevents the shim 810 from being removed from the bottom of blade 802.In addition, pins or other structure (not seen in FIG. 8G) operate torestrict movement of shim 810 towards the top of blade 802. In thismanner, intradiscal shim 810 has a limited range of sliding motionrelative to blade 802, but is not removable from blade 802 througheither the top (proximal) or bottom (distal) ends of blade 802.

FIGS. 8H and 8I depict an anchoring shim 824 that may be used with theretractor devices described herein. The anchoring shim 824 includes abody 826 that is configured to slide within the groove 804 of the blade802. The blade 802 includes inner edges 818 that substantially surroundor engage wings 820 of the anchoring shim 824, similar to the blades andwings depicted in FIG. 8G, above. Unlike the shims of FIGS. 8A-8G,however, the anchoring shim 824 lacks any rear projections to engagewith the ratcheted groove 804. Instead, the anchoring shim 824 isconfigured to slide unimpeded along the blade 802. Tabs 828 may engagewith an elongate tool to move the anchoring shim 824 within the groove804 or to hold the shim 824 steady. Unlike the tabs 806 depicted above,however, these tabs 828 need not be deflected inward to move the shim824. Instead, the tabs 828 serve as a point of connection with theelongate tool. In some embodiments, the elongate tool also engages theblade inner edges, wings, grooves, or similar structure of the blade foradditional control of shim movements when using the elongate tool.Extending from and through the body 826 is a fastener 830 that may beused to anchor the blade 802 to a vertebral body. In the depictedembodiment, fastener 830 is a threaded screw with a tool engagingproximal portion. Other fasteners also may be used, including pins,elongate wires, or the like. In some embodiments, the anchoring shim 824is utilized on the cranial or caudal blades, for coupling of thefastener 830 to a vertebral body. A head of the fastener 830 may beactuated by a tool, such as a hex driver or other device for securingthe fastener 830 to bone. Once one of either the cranial or caudalblades are anchored via the shim 824, opening of the retractor devicearms will result in the unanchored blade moving away from the anchoredblade, thus moving a central axis of the surgical corridor away from theanchored blade.

FIGS. 8J and 8K depict another embodiment of an anchoring shim 832. Thisanchoring shim 832 utilizes deflectable tabs 808 to selectively locateassociated projections (not shown) within the ratcheted groove 804(similar to the shims of FIGS. 8A-8G). Two fastener retention ears 834are located on either side of the vertebral screw 830. This anchoringshim 832 differs additionally from the anchoring shim 824 of FIGS. 8Hand 8I in that the fastener holding force provided by the retention ears834 is less than that provided by the enclosed body 824 of the firstanchoring shim 824 of FIGS. 8H and 8I. For example, the shim 832 mainbody and ears 834 generally surround fastener 830 on three sides,leaving a gap on one side. As a result, a force applied to blade 802 ina direction generally opposite this gap may allow shim 832 to disengagefrom fastener 830. In some circumstances, this may be desired. In othercases, the anchoring shim 832 may be used when the blades 802 havealready been opened.

FIGS. 8L and 8M depict yet another embodiment of an anchoring shim 836,that also utilizes deflectable tabs 808 to selectively locate associatedprojections (not shown) within the ratcheted groove 804 (similar to theshims of FIGS. 8A-8G). A single fastener retention hook 838 wraps atleast partially around the fastener 830. Accordingly, this anchoringshim 836 may provide more screw holding force than the embodimentdepicted in FIGS. 8J and 8K. Regardless of the differences, use of eachof the anchoring shims described herein may be desirable at differentstages of a surgical procedure, depending on particular workingconditions, clearance issues, or surgeon preferences.

Yet another anchoring shim 840 is depicted in FIG. 8N. This anchoringshim 840 is similar in configuration to the anchoring shim 824 of FIGS.8H and 8I, in that it may freely slide within the groove 804 of theblade 802. Further, housing 826 has a channel or hole therethrough toreceive the fastener 830. Again, fastener 830 may be a threaded screw, anon-threaded screw, a pin, an elongate wire, or the like. Connected tothe housing 826 is an elongate arm 842. Arm 842 is coupled to thearmature 844 to which the blade 802 is attached. In this manner, oncethe fastener 830 is anchored to the vertebral body, the blade 802 may bedisconnected from the arm 844 and from the shim 840 and removed from thesurgical corridor. This may occur, for example, by removing screw 612holding the proximal end of blade 802 to armature 844, and lifting theblade 802 vertically to disengage blade 802 from shim 840. The elongatearm 842 allows the armature 844, and thus the retractor, to remainsecured to the anchoring shim 840. Accordingly, access to the interiorof the surgical corridor may be improved with the blade 802 removedtherefrom.

In another embodiment, one or more of the retractor blades comprisetelescoping blades. In such an embodiment, the retractor blade includesa proximal-most portion coupled to the retractor arm and a distal-mostportion. The proximal-most portion and the distal-most portion overlapin a telescoping or nestled fashion to allow the retractor blade to havea variable overall length. In some embodiments, the telescoping bladecomponents have a slidable relationship, but are non-separable, toensure they stay connected while opening or holding the surgicalcorridor. In some embodiments, shims described herein have a boss, peg,or similar feature on the back of the shim which slides in a groove orslot in the blade to which it is coupled. The groove has a closed distalend that operates as a travel stop for the shim boss or the like. Inthis manner, the boss and groove combination, or similar structure,prevents the shim from sliding out the distal end of the blade.

FIGS. 9A-9C depict a method of performing a surgical procedure with thesystems and devices described herein. FIG. 9A depicts a transversecross-sectional view 900 of the torso 902 of a human body. For a lateralsurgical procedure, the patient is positioned on a surgical table andx-rays, such as true lateral and anterior-posterior, may be taken. Thesurgeon may then make a first incision in the desired location. Theinitial distraction corridor (i.e., separation of the muscle fibers) ismade using blunt dissection, as depicted in FIG. 9A. Blunt dissectionrequires a surgeon to digitally penetrate the torso 902 with one or morefingers 904. Using blunt dissection, a posteriorly-directed trajectory(aiming for the transverse process) is used to enter the retroperitonealspace 906. Once the retroperitoneal space 906 has been entered, thetissue is distracted into the free space of the retroperitoneum. Theperitoneum may be moved anterior with the fingers 904 and bluntdissection continued to palpate to the transverse process posteriorly.The finger 904 may be slid forward to the retro-psoas recess and overthe dome of the psoas to ensure retroperitoneal viscera have been safelyretracted anteriorly. In general, the distraction corridor is formed ina direction generally towards the spine 908.

FIG. 9B depicts an anterior view of a spine 908. After the bluntdissection depicted in FIG. 9A, a first dilator 910 is inserted throughthe incision. The location of the first dilator 910 may be verifiedusing lateral fluoroscopy. It is desirable that the first dilator 910 betargeted to the center of the intervertebral disc space 912. The firstdilator 910 may be advanced through the psoas muscle (not shown) using arotating motion. In some cases, the first dilator 910 may be locatedbetween about the center and about the posterior-third of the disc space912, and the position verified using lateral fluoroscopy. Once the firstdilator 910 is an acceptable position, a K-wire 914 may be insertedthrough the center thereof and into the disc space 912. The K-wire 914may be inserted approximately half-way across the disc space 912 toassist in securing the access entry point. Again, anterior-posterior andlateral fluoroscopy may be used to ensure the proper location of theK-wire 914 and the first dilator 910. Thereafter, a second dilator (notshown in FIG. 9B) may be advanced over the first dilator 910, using arotating motion.

FIG. 9C depicts a perspective view of a spine 908. After insertion ofthe second dilator 916 over the first dilator 910, the retractor blades918 of the retractor device 920 are placed around the second dilator 916and advanced downward into position. Position of the blades 918 may beverified as in-line with the disc space using fluoroscopy. It isgenerally desirable that the retractor 920 be parallel to the disc space912 and the retractor working channel (the space between the blades 918)be aligned with the disc space 912. In some cases, such as when workingaround other bony structure (e.g., ribs, iliac crest, etc.), theretractor 920 may be angled in the cranial/caudal direction relative tothe patient. The retractor 920 may next be secured in place byconnecting an articulating arm (not shown) to one of the retractorconnection points. The articulating arm is also connected to a generallyfixed or stable structure, such as the surgical table, to provide asteady platform for retractor 920.

The surgical corridor may now be expanded and otherwise altered asdesired in accordance with the manipulations of the retractor device 920described above. Typical functions include separation of thecranial/caudal blades, retraction of the posterior blade, toeing of theblades, etc. Once the retractor blades 918 are opened to the desiredposition, the first dilator 910, the second dilator 916, and the K-wire914 may be removed. Once these components are removed, an implantinsertion procedure may be performed. Any number of actions may betaken, in almost any order, to insert an implant. For example, anintradiscal shim (as depicted above), may be extended out of theposterior blade in which it is located during insertion and into thedisc space 912. The position of this element may be verified usinganterior-posterior fluoroscopy. Additionally, widening or lengtheningshims may be advanced as needed. If desired, the handle 922 may beremoved from the retractor device 920. Annulotomy and discectomyprocedures may then be undertaken to remove the disc material, and anappropriately sized implant may be inserted. After implantation, theretractor blades 918 may be closed and removed from the body and thesurgical corridor sutured closed.

FIG. 9D depicts a perspective view of the retractor device 920 with theblades 918 in an open position. In this figure, the spine has beenremoved for clarity. As described elsewhere herein, rotation R of themain actuator 926 of the handle 922 opens the cranial and caudal arms928. Resistance of the patient tissue, however, may make difficult therotation R of the main actuator 926 about the handle axis A. In thatcase, the posterior actuator 930 may be withdrawn from the handle 922along the axis A. Thereafter, a tip of the posterior actuator 930 may beinserted into one of several torque points 932 about an outer diameterof the main actuator 926. A torque T may be applied to the posterioractuator 930, such that actuator 930 t acts as a lever to make foreasier rotation R of the main actuator 926. Once the arms 928 have beenopened to the desired position, the posterior actuator 930 may bereturned to its original location on the handle 922. As previouslydescribed, in some embodiments main actuator 926 operates a worm geardrive to allow blades 918 to be opened a desired amount and maintained.

FIG. 9E depicts a perspective view of the retractor device 920 with theblades 918 in an open position. In this figure, the spine has beenremoved for clarity. Forces acting on the blades 918 by the body tissuemay also cause the retractor device 920 to move undesirably. To overcomesuch forces, a pivot lever 934 may be connected to one of the armconnections 936 (that are typically used for connection to anarticulating arm, as described above) and a torque T′ applied. This willrotate R′ the entire device 920 about the device axis A, thus improvingthe ability to position the device 920 as desired. This may beespecially helpful when attempting to anchor any of the blades 918 tothe vertebrae with the anchoring shims described above. Pivot lever 934also may be used to rotate retractor 920 about the dilators to aid inthe insertion of retractor 920 towards the surgical site, or provide ahand-hold for a user to better hold, support or manipulate retractor920.

FIG. 9F depicts other components that may be utilized with the retractordevice 920 to fix the position of the device 920 within the body and/orto create or maintain a desired operative opening. As shown, a spanmember 938 connects to the free ends of both of the articulating arms928. In some embodiments, the span 938 defines a slot 940 through whichone or more anchor rods 942 may be passed. The anchor rods 942 may bescrewed into vertebral bodies, typically on either side of a target disc912. In addition to fixing the position of the device 920 relative tothe spine 908, the anchor rods 942 may also be used to hold back tissuethat may creep into the space between the cranial and caudal blades 918once opened.

In an alternative embodiment, an additional or optional paddle 944 isprovided to help create or maintain a desired operative window. Forexample, and as depicted in FIG. 9G, paddle 944 may be coupled to a span946 placed between the two pivoting arms (not depicted in FIG. 9G) afterthe surgical access corridor is created. The span 946 may be similar oridentical to the span 938 of FIG. 9F. In general, the paddle 944 ispositioned generally opposite the posterior blade, although it could becoupled to the span 938 at any location. In this manner, the paddle 946helps maintain an additional side, such as an anterior side, of thesurgical access corridor. The paddle may simply be a static blade orrod, or other elongate member having any cross-sectional profile. In thedepicted embodiment, the paddle 944 includes an elongate rod 948 havinga wider base 950. Opposite the wider base 950 is a handle 952 that maybe moved as desired to position the paddle 944. A fastener member, shownas a threaded knob, operates to couple elongate rod 948 to the span 946.The fastener member further may couple the elongate rod 948 to controlthe depth of paddle 944 relative to the surgical location. In mostembodiments, the paddle 944 lacks any additional structure that wouldenable use thereof with shims. However, in alternative embodiments, suchstructure (grooves, etc.) may be incorporated if desired. Since thepaddle 944 is generally used to prevent tissue creep from the spacebetween the cranial and caudal blades, any type of rigid structure thatcan hold tissue is sufficient.

The methods depicted in FIGS. 9A-9C may be modified by the incorporationof known neuromonitoring techniques. Neuromonitoring is not required toperform the procedures described herein, but may be desirable and istherefore incorporated at the surgeon's discretion. A number ofdifferent neuromonitoring systems may be utilized. Manufacturers ofacceptable systems include Caldwell Laboratories, Inc., of Kennewick,Wash. Caldwell Laboratories, as well as other manufacturers, alsomanufactures monitoring probes (also referred to as electrodes) that maybe utilized in conjunction with various surgical instruments or alonefor treatment or diagnostic purposes. These electrodes are typicallydisposable elements that may be inserted into the body as required. Thedilators described herein, as well as the retractor blades, include oneor more channels to receive such probes. The probes may be insertedbefore or after insertion of the particular component into the body,again at the surgeon's discretion. Neuromonitoring techniques, inconjunction or discrete from surgical implements, are well-known topersons of skill in the art. Regardless, when electrodes are used inconjunction with the components described herein, the electrode istypically first inserted into the appropriate channel of the component.Once the component is inserted into the desired depth within the body,the neuromonitoring equipment is then activated and the response fromthe nerves detected. Proper operation of neuromonitoring equipmenttypically requires that the component first be inserted, stopped at adesired position, then neuromonitoring performed. This gives the surgeonthe feedback necessary to adjust the position of the component so as toavoid the nerves. This may be performed in steps, advancing thecomponent a certain distance, stopping advancement, monitoring, andrepeating advancement as required.

FIGS. 10A and 10B depict a method 1000 of using a retractor system.Although the method is described in the context of lateral-approachspinal surgery, it should be noted that the systems and methodsdescribed herein may be used in virtually any surgery where limitedmuscular trauma is desired. In surgeries where limited, controlledseparation of muscle fibers is desirable, the retractor system describedherein may be particularly advantageous. Although described inconjunction with FIGS. 10A and 10B, the order of steps or procedures maydiffer from that depicted. First, as previously depicted in FIG. 9A, thepatient is properly positioned and an incision is made in the desiredlocation and the initial distraction corridor is formed via blunt (i.e.,digital) dissection (operation 1002). After the initial distractioncorridor is formed, a first dilator is inserted (operation 1004).Thereafter, a K-wire may be inserted via the lumen of the first dilatorand secured to the disc space (operation 1006). This helps preventmovement of the dilator, thus keeping that element (and the subsequentelements) properly positioned within the body. Thereafter, a seconddilator is inserted over the first dilator (operation 1008), such thatthe first dilator (and K-wire located therein) are located within thelumen of the second dilator. If desired, additional dilators may be usedto create a larger corridor before insertion of the retractor. Aretractor device is then inserted over the second dilator (operation1010). During insertion of the retractor device, the arms and blades ofthe device are in the closed position (that is, the position where eachblade is located as close as possible to the two adjacent blades).Blades containing the intradiscal shim have a sufficiently low profileto allow for insertion of the retractor with the intradiscal shim.Further, the low profile of the intradiscal shim and the shim extensiontool allows the shim to be advanced from a retracted position to anextended position after the retractor has been inserted and before thedilators have been removed. This helps secure the retractor with theintradiscal shim between two bony structures, such as vertebrae, beforethe dilator(s) and/or K wire is removed. Additionally, any blades thatmay have toeing functionality should be set such that the blades areparallel to the direction of insertion. During insertion, all three ofthe blades of the retractor device are inserted simultaneously.

Once the retractor device is inserted to the desired depth, the K-wireand dilators may be removed from the area between the blades (operation1012). To secure the retractor device at the desired location, anarticulating arm connected to the surgical table or other fixed elementmay be connected to one of the connection points on the retractor devicebody or posterior arm (operation 1014). In some embodiments, operation1014 occurs prior to operation 1012. In addition to the articulatingarm, an intradiscal shim located within the posterior blade may also beextended into the disc space to further secure the device in the desiredlocation. The operation of extending the intradiscal shim is describedbelow. Once the retractor device is in the desired position, the cranialand caudal arms (and, therefore the cranial/caudal blades) may beexpanded and the posterior blade retracted (operation 1016). Once thevarious blades are expanded to the desired distance, a surgicalprocedure may be performed.

However, the retractor device described herein includes, or may beutilized with, a number of supplemental components to increaseversatility of the device. This versatility allows a surgeon to modifythe surgical corridor (operation 1018) as required or desired to addressparticular internal anatomical conditions, or to otherwise improveusability of the retractor device. For example, and as noted firstabove, the intradiscal shim may be extended from its stored position inthe posterior blade to further fix the position of the device relativeto the spine (operation 1018 a). Other shims may also be used inconjunction with the cranial and caudal blades. For example, thewidening and/or lengthening shim may be used to supplement the blades.In some embodiments, the shims are loaded into their respective bladesafter the retractor blades have been inserted into the patient. Thisoccurs, for example, by inserting the shim down through the proximal end(top) of the blade using a shim inserter tool. Alternatively, at leastsome of the shims have a sufficiently low profile to be inserted intothe blades prior to insertion of the blades into the patient. Aspreviously noted, there may be a small gap between one or more blades asthe blades are inserted over the largest dilator. To use either of thewidening or lengthening shims, the shim is placed into the shim groovein the desired blade, then advanced down towards the end of the blade(operation 1018 b). The tab and groove interface of the shim and bladeallows the shim to be advanced as far as required or desired, andresists or prevents undesired movement of the shim back towards theproximal end of the blade. The cranial and caudal blades may also betoed out to increase the area of the corridor proximate the spine(operation 1018 c). If more robust fixation of the blades within thesurgical corridor is desired, anchoring shims may be used to engage thevertebra (operation 1018 d). Typically, the anchoring shims are insertedafter the blades have been inserted into the patient and opened orseparated at least enough to allow shim insertion. Alternatively oradditionally, one or more rods may also be anchored (operation 1018 e).Another modification of the corridor includes utilizing the supplementalpaddle between the cranial and caudal arms to prevent tissue creep intothe space therebetween (operation 1018 f). Of course, any or all ofthese operations may be performed at any desired time to modify,enhance, or otherwise support the surgical corridor.

Regardless, once the desired corridor is obtained, an implant insertionprocedure is performed (operation 1020). The steps of the implantinsertion procedure would be known to a person of skill in the art andare not described further. Once the implant insertion procedure iscompleted, shims and other optional features are retracted or removed.The retractor blades may be closed and the device removed from the body,allowing the surgeon to close the incision (operation 1022). Asdescribed above, neuromonitoring may be utilized during any point of themethod, at the discretion of the surgeon.

Materials utilized in the manufacture of the retractor system may bethose typically used in surgical equipment. Stainless steel, titanium,and other robust metals that may be sterilized may be used. Inapplications where fluoroscopy is desirable or required during theprocedure (e.g., in the spinal surgery procedures described herein),radio-lucent materials may be particularly desirable. In thoseapplications, aluminum, anodized aluminum, and rigid polymers may beutilized. In some embodiments, the retractor blades comprise aluminumwhich has been anodized with a hard coat anodizing process to create anelectrical insulated material. Such blades may be useful, for example,in the event the surgeon prefers to use electrical nerve monitoringequipment. Carbon fiber-reinforced polymers may be particular useful, asthey are lightweight, extremely strong, and may be sterilized. Ofcourse, retractor systems utilizing a combination of materials may beused. For example, radio-lucent materials may be used for the blades andless expensive radio-opaque material may be utilized for the elongateelement and armatures. Use of radio-lucent materials for the coverplate, armatures, and body may be particularly advantageous, as aninstrument so configured will be less visible in lateral x-rays.Additionally, radio-opaque materials may be impregnated in discretelocations of components manufactured of radio-lucent materials such thatposition of certain parts of the system may be visible duringprocedures, without impeding overall visibility.

While there have been described herein what are to be consideredexemplary and preferred embodiments of the present technology, othermodifications of the technology will become apparent to those skilled inthe art from the teachings herein. The particular methods of manufactureand geometries disclosed herein are exemplary in nature and are not tobe considered limiting. It is therefore desired to be secured in theappended claims all such modifications as fall within the spirit andscope of the technology. Accordingly, what is desired to be secured byLetters Patent is the technology as defined and differentiated in thefollowing claims, and all equivalents.

What is claimed is:
 1. A surgical retractor comprising: a retractorbody; a first armature pivotably coupled to the retractor body at afirst pivot point, the first armature including gear teeth proximate thefirst pivot point, and the first armature rotatable between a firstclosed position and a first open position; a second armature pivotablycoupled to the retractor body at a second pivot point spaced apart fromthe first pivot point, the second armature including gear teethproximate the second pivot point, and the second armature rotatablebetween a second closed position and a second open position; atranslatable armature disposed between the first pivot point and thesecond pivot point, the translatable armature translatable between athird closed position and a third open position; a first actuatorcoupled to the retractor body and aligned with the translatablearmature, the first actuator coupled to a central drive mechanismoperable by the first actuator to simultaneously engage the gear teethof each of the first armature and the second armature to move the firstarmature and the second armature independent of the translatablearmature; and a second actuator coupled to the retractor body androtatable to linearly translate the translatable armature.
 2. Thesurgical retractor of claim 1, further comprising: a top cover plate anda bottom cover plate opposing the top cover plate, the top cover plateand the bottom cover plate secureable to the body to limit access to thedrive mechanism.
 3. The surgical retractor of claim 2, furthercomprising: a first pin associated with the first armature, wherein thetop cover plate includes a first slot configured to receive the firstpin to limit rotation of the first armature relative to the body.
 4. Thesurgical retractor of claim 3, further comprising: a second pinassociated with the second armature, wherein the top cover plateincludes a second slot configured to receive the second pin to limitrotation of the second armature relative to the body.
 5. The surgicalretractor of claim 3, wherein the first slot comprises an arcuate shape.6. The surgical retractor of claim 2, wherein one of the top cover plateand the bottom cover plate is comprised of a radio-opaque material. 7.The surgical retractor of claim 1, wherein one or more of the first andsecond actuators are removable.
 8. The surgical retractor of claim 1,wherein the translatable armature is translatable independent of thefirst armature and the second armature.
 9. The surgical retractor ofclaim 1, wherein one of the first and second armatures and body iscomprised of a radio-opaque material.
 10. The surgical retractor ofclaim 1, wherein one of the first and second armatures and body iscomprised of a radio-lucent material.
 11. A surgical retractorcomprising: a retractor body; a first armature rotatably coupled to theretractor body at a first pivot point, the first armature including gearteeth adjacent the first pivot point, and the first armature rotatablebetween a first closed position and a first open position; a secondarmature rotatably coupled to the retractor body at a second pivot pointspaced apart from the first pivot point, the second armature includinggear teeth adjacent the second pivot point, and the second armaturerotatable between a second closed position and a second open position; atranslatable armature disposed along a central axis, the translatablearmature translatable between a third closed position and a third openposition; a first actuator coupled to the retractor body and alignedalong the central axis, and actuatabie to operate a central drivemechanism to simultaneously engage the gear teeth of the first armatureand the gear teeth of the second armature to rotate the first armatureand the second armature independent of the translatable armature; asecond actuator coupled to the retractor body and rotatable to linearlytranslate the translatable armature.
 12. The surgical retractor of claim11, wherein the gear teeth of each of the first armature and the secondarmature are disposed along an arcuate surface of the first armature andthe second armature, respectively.
 13. The surgical retractor of claim11, further comprising: a top cover plate and a bottom cover plateopposing the top cover plate, the top cover plate and the bottom coverplate secureable to the body to limit access to the drive mechanism. 14.The surgical retractor of claim 13, further comprising: a first pinassociated with the first armature, wherein the top cover plate includesa first slot configured to receive the first pin to limit rotation ofthe first armature relative to the body.
 15. The surgical retractor ofclaim 14, further comprising: a second pin associated with the secondarmature, wherein the top cover plate includes a second slot configuredto receive the second pin to limit rotation of the second armaturerelative to the body.
 16. The surgical retractor of claim 15, whereineach of the first slot and the second slot comprise an arcuate shape.17. The surgical retractor of claim 15, wherein the first armature andthe second armature are rotatable to any position defined by the firstslot and the second slot, respectively.
 18. The surgical retractor ofclaim 11, wherein the gear teeth of each of the first armature and thesecond armature are disposed along an arcuate surface of the firstarmature and the second armature, respectively.
 19. The surgicalretractor of claim 11, further comprising: a first blade coupleable to adistal portion of the first armature; and a toeing screw engageable withthe first armature and operable to adjust a toe angle of the firstblade.
 20. A surgical retractor comprising: a retractor body; a firstarmature pivotably coupled to the retractor body at a first pivot point,the first armature rotatable between a first closed position and a firstopen position; a second armature pivotably coupled to the retractor bodyat a second pivot point spaced apart from the first pivot point, thesecond armature rotatable between a second closed position and a secondopen position; a translatable armature disposed between the first pivotpoint and the second pivot point, the translatable armature translatablebetween a third closed position and a third open position; a firstactuator located at least partially within the retractor body andsubstantially aligned with the translatable armature along a centralaxis, the first actuator configured to operate a central drive mechanismto engage gear teeth of each of the first armature and the secondarmature to move the first armature and the second armature about thefirst pivot point and the second pivot point, respectively, independentof the translatable armature; a second actuator coupled to the retractorbody and rotatable to linearly translate the translatable armature.